VecScatterCreateToZero

[Matthew Knepley]

Use the coodinate DA.

  Matt

On Fri, Aug 28, 2009 at 2:54 AM, nicolas aunai <nicolas.aunai at gmail.com>wrote:

> Hi,
>
> Hum... Yes and no. This function does indeed create a VectorScatter
> that allows to go from parallel to sequential and natural vectors, but
> the sequential vectors must but structured to receive the DA data. For
> example a 2D DA with 3 degree of freedom will require a specific
> vector with a global size equal to nx*ny*3
>
> I want to scatter the coordinates vector obtained with the function
> DAGetCoordinates(), which is of size nx*ny*2.
>
> This is the reason why I was not using the DACreateNaturalVector()
> function and then VecScatterCreateToZero(), the natural vector being
> created has a wrong size.
>
>
>
>
>
> 2009/8/27 Matthew Knepley <knepley at gmail.com>:
> > This should be good enough
> >
> >
> >
> http://www.mcs.anl.gov/petsc/petsc-as/snapshots/petsc-current/docs/manualpages/DA/DAGlobalToNaturalAllCreate.html
> >
> >      Matt
> >
> > On Thu, Aug 27, 2009 at 12:51 PM, nicolas aunai <nicolas.aunai at gmail.com
> >
> > wrote:
> >>
> >> Hello,
> >>
> >>
> >> I have a problem using 'VecScatterCreateToZero'. I attach to this
> >> email a test code that illustrates the problem. I create a 2D DA then
> >> I ask for the coordinates (that have been set just before), which are
> >> returned in a global vector. I want to write the coordinates in a
> >> file, so I use 'VecScatterCreateToZero' to put all the values in
> >> sequential vector. It seems to work fine but sometimes (depending on
> >> the number of proc used) the coordinates in the sequential vectors are
> >> ordered differently.
> >>
> >> to run the code and see the problem :
> >>
> >> mpiexec -n 4 ./vecdacoord > problem.txt
> >>
> >> I have attached problem.txt too.
> >>
> >> Is someone can explain to me how I could obtain my coordinates in a
> >> natural order ?
> >>
> >>
> >> Thx
> >
> >
> >
> > --
> > What most experimenters take for granted before they begin their
> experiments
> > is infinitely more interesting than any results to which their
> experiments
> > lead.
> > -- Norbert Wiener
> >
>



-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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